I think Junji Ito is one of the most interesting, but also unappreciated authors we have. His stories isn't really mean to be scary I think, to me he more likely plays with grotesque and obscurity, trying out new ideas for monsters he draws and I love it. Rather than being scared, you may feel disturbed, disgusted and intrigued (or maybe it's just me). I personally find 'Secret of the Haunted Mansion' the best one, especially because it's a continuity to other Junji Ito's series called 'Souichi Diary of Delights' which is one of my favorite mangas in general.